Supervised annunciator

ABSTRACT

A completely supervised alarm system having an alarm panel and a remote annunciator unit which is interconnected to the alarm panel. The alarm system is characterized by a memory capability, the ability to add additional circuits to be monitored without additional wiring between the main alarm and remote annunciator panels and without disturbing preexisting supervisory wiring. The system is also characterized by employment of a bidirectional silicon controlled rectifier for supplying energization for audible warning devices and by use of a single relay for the monitoring for open and ground conditions on all interconnecting wiring and on the annunciator internal circuitry.

United States Patent 3,478,352 1 1/1969 Eisenberg 340/409 FOREIGNPATENTS 954,192 4/1964 Great Britain 340/409 Primary ExaminerThomas B.Habecker Attorney-Colton & Stone ABSTRACT: A completely supervised alarmsystem having an alarm panel and a remote annunciator unit which isinterconnected to the alarm panel. The alarm system is characterized bya memory capability, the ability to add additional circuits to bemonitored without additional wiring between the main alarm and remoteannunciator panels and without disturbing preexisting supervisorywiring. The system is also characterized by employment of abidirectional silicon controlled rectifier for supplying energizationfor audible warning devices and by use of a single relay for themonitoring for open and ground conditions on all interconnecting wiringand on the annunciator internal circuitry.

SUPERVISED ANNUNCIATOR BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention relates to alarm systems. Moreparticularly, the present invention is directed to the provision of acompletely supervised, multicircuit annunciated alarm system having anannunciator unit and a main alarm board which are located remote fromone another. Accordingly, the general objects of the present inventionare to provide novel and improved methods and apparatus of suchcharacter.

2. Description of the Prior Art While not limited thereto in itsutility, the present invention is particularly well suited foremployment as a fire alarm system. Previously available fire alarmsystems of the type which had a main alarm panel and an annunciatorpanel have either ignored the necessity of supervising theinterconnecting wiring between the control or alarm panels and theremote annunciators or have employed at least one relay and itsassociated circuitry to supervise each line interconnecting the twounits. As is well known, electromechanical devices such as relays aresusceptible to failure and/or faulty performance due to such causes ascontact pitting or corrosion. Accordingly, prior art alarm systems ofthe type being discussed have, from the standpoint of reliability, beensuspect.

An additional problem which has plagued the prior art has been aninability to provide an alarm system characterized by ease of isolationand analysis of fault conditions. The desire for ease of maintenance isnecessitated by the need to enable maintenance by personnel with limitedtechnical knowledge.

A further deficiency of prior art alarm systems has been the inabilityto add detector circuits without providing additional interwiringbetween the main alarm panel and remote annunciators and withoutdisturbing existing supervisory wiring. Thus, in the prior art, themodification of an alarm system to enable it to exercise supervisionover an additional detector circuit, as might for example be required bya building addition, has been possible only through the extensiverewiring of the alarm panel and/or the annunciator panel and theinterconnecting wiring between the two.

SUMMARY OF THE INVENTION The present invention comprises a completelysupervised, multicircuit, annunciated alarm system which employs asingle supervisory relay for supervising an unlimited number of externalcircuits as well as internal annunciator circuits. The system of thepresent invention also has a memory capability and therefore willmaintain an annunciated alarm condition even though the detector whichoriginally called for the sounding of the alarm is completely destroyed.As an added feature, the present system employs a bidirectional, siliconcontrolled rectifier as ballast for audible alarm devices which arelocated on the alarm panel thereby providing for increasedperceptibility of the alarms. The present invention is alsocharacterized by flexibility in that additional detector circuits may beadded merely through the addition of a supervisory diode to theannunciator panel internal circuitry.

It is therefore an object of the present invention to provide acompletely supervised multicircuit annunciated fire alarm system.

It is another object of the present invention to provide a completelysupervised multicircuit annunciated alarm system employing a minimum ofrelays.

It is a further object of the present invention to provide amulticircuit annunciated alarm system characterized by a minimum amountof interconnecting wiring between the alarm or signal control panel andthe annunciator.

It is yet another object of the present invention to provide amulticircuit, annunciated fire alarm system having a memory capability.

It is still another object of the present invention to provide amulticircuit,annunciated alarm system employing a single supervisoryrelay in the alarm panel to supervise an unlimited number of externalcircuits and the internal annunciator circuits for open or groundfaults.

It is another object of the present invention to provide a supervised,multicircuit annunciated alarm system which is sensitive to opencircuits and ground faults within the annunciator panel circuitry or onexternal, interconnecting wiring.

It is also an object of the present invention to provide a completelysupervised multicircuit annunciated alarm system characterized by easeof maintenance.

It is yet another object of the present invention to provide amulticircuit alarm system which will accept additional detector circuitswithout disturbing existing supervisory wiring.

It is still another object of the present invention to provide amulticircuit, supervised, annunciated alarm system to which additionaldetector circuits may be added without additional interwiring betweenthe alarm and annunciator panels.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects andadvantages of the present invention will .become readily apparent tothose skilled in the art by reference to the accompanying drawing whichis a schematic diagram of a preferred embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,the supervised annunciated alarm system of the present inventioncomprises a fire alarm unit or panel, indicated generally at 10, and anannunciator unit or panel, indicated generally at 12. Power, from astandard l l5/230 volt alternating current source is supplied to thealarm panel as shown. The alarm and annunciator units are interconnectedby means of conductors M, 16, 18, 20, 22 and 24. Conductors l4 and 16respectively connect one side and the neutral of the alternating currentsource to the annunciator panel 12 thus furnishing power for theannunciator. A plurality of audible alarm devices, shown as seriesconnected horns 26, 28 and 30 are connected to the alarm panel 10, thehorns being physically located at appropriate watch stations.

Current supplied to annunciator panel 12 via conductor M is delivered,via the normally closed contacts of switch S1, through fuse Fl to afirst pair of normally open contacts 32 of relay RYl. Under normalconditions, with the solenoid of relay RYI deenergized, current willflow via an external conductor 3d from the line side contact of normallyopen contacts 32 to an end-of-line resistor R1 before passing throughthe solenoid of relay RYl. Current passing through the solenoid of relayRY! also passes through an annunciator lamp Ll, resistor R2 and thenceback to the neutral of the AC supply via conductor 16. Theabove-described complete circuit for current from the external powersupply through the annunciator panel provides a small supervisorycurrent through all the elements previously described in the annunciatorcircuit and it is to be noted that duplicate parallel circuitry isprovided for annunciator panel relays RYl and RYl. In practice, theremay be any number of parallel connected relay circuits. It is to benoted that, in the interest of clarity, the external detector circuitsand their end-of-line resistors have not been shown for the RYl' andRYI" relay circuits.

Any open condition due to failure of any of the previously describedcomponents a failure of or at the power supply source, or any groundcondition on external lines which would cause the fuse Fll to open willdisrupt the current flow through resistor R2. In order to accomplishsupervision of the RYl annunciator relay circuits, normally reversebiased D1 diodes have their cathodes connected to the junction betweenresistor R2 and lamp L1. The anodes of the D1 diodes are connected, viaconductor 38, to the base of a transistor Q1. The reverse biasing of theD] diodes is accomplished as follows. When the polarity of the powersupply source is such that a positive potential appears on conductor 14,a diode D2, which has its anode connected to switch I by means ofconductor 40,

will be forward biased. Diode D2 will thus conduct and a secondarycurrent path will be provided back to the neutral terminal of the source(conductor 16) via the base to emitter circuit of normally conductivetransistor 01 and its emitter resistor R4. Under normal conditions, thevoltage drop across resistor R2 will provide a reverse bias on Diode Dl.

Restated, the circuit parameters are chosen so that the voltage dropacross resistor R2 is slightly greater than the voltage appearingbetween neutral conductor 16 and the base of transistor and thus diodeD1 cannot conduct under normal conditions. However, should there be anydisruption of the current through the resistor R2, diode D1 will nolonger be reverse biased and will conduct. Conduction of diode D1provides a shunt path from the base of transistor 01 through resistor R2to neutral conductor 16. The establishment of this shunt path by theremoval of the reverse bias on diode D1 causes a decrease in the forwardbias applied to the base of transistor Q1 thus causing transistor 01 tobe gated off. In the manner to be described below, the turning off oftransistor 01 will cause energization of a warning buzzer on the alarmpanel.

As should now be obvious, by tracing parallel paths through the similarcircuits of relays RYl' and RYl, a disruption of normal conditions inany of the circuits will cause a shunt condition for the forward bias onthe base of transistor ()1. Thus, it may be seen that a theoreticallyunlimited number of similar circuits may be supervised for open and/orground fault conditions since any circuit can provide a shunt paththrough its respective resistor R2 to decrease the forward bias ontransistor 01.

Turning now to fire alarm panel 10, the operation of warning buzzer 42upon the shunting of the bias on transistor 01 will first be described.Current is supplied to buzzer 42 from the alternating current source viathe contacts 43 of relay RY2. lt is to be noted that the solenoid ofrelay RY2 is normally energized and thus the circuit from the powersupply to buner 42 is normally interrupted. Energizing current for relayRY2 is supplied as follows. Current from the side of the alternatingcurrent source which is of the opposite polarity to the side which isconnected to the line side of the contacts 43 of relay RY2 is deliveredto the alarm panel as previously described and flows through fuse F2 andthe normally closed contacts of test and reset switch S2. The thusdelivered current then passes through lamp L2 and a bidirectional,silicon controlled rectifier or Triac indicated generally at 44. FromTriac 44, assuming the source polarity to be proper, current will passthrough resistor R and series connected diode D3 and then, via externalconductor 22, to the annunciator panel. In the annunciator circuit, thecurrent delivered via conductor 22 will be passed by Zener diode ZDl,will be delivered back to the alarm panel via conductor 24 and will flowthrough the solenoid of relay RY2 and back to the neutral of thealternating current source.

On opposite half cycles of the AC supply voltage, that is when thepolarity at the line side of fuse F2 is negative, current flow throughthe relay RY2 energization circuit is blocked by diode D3 which will nowbe reverse biased. However, during this time the magnetic field collapseof the solenoid of relay RY2 generates a voltage of such polarity as tocause current to flow from the neutral or grounded terminal of thesolenoid through external line 16 to the annunciator panel and thencethrough diode D4 which will be forward biased at this time. Currentpassed by diode D4 will be delivered back to the solenoid of relay RY2in the alarm panel by conductor 24 therefore maintaining current throughthe relay coil and thus preventing energization of buzzer 42.

It is especially to be noted that a break in either of lines 16 or 24will open the above-described field collapse circuit thereby causingrelay RY2 to chatter since it will then be energized every half cycle ofthe alternating current supply voltage. The chattering of the contactsof relay RY2 will cause buzzer 42 to sound thereby providing anindication of trouble. Similarly, the accidental grounding of conductor24 will also disrupt current fiow to relay RY2 causing it to drop outand complete the circuit to buzzer 42 thereby causing the warning buzzerto sound.

As mentioned above, transistor O1 is normally in a conducting state. Thevoltage drop across the collector circuit resistor R6 of transistor Q1will limit the forward bias on transistor 02 thus maintaining thistransistor in a nonconductive state. However, if a fault conditionoccurs in the circuitry for supplying current to the annunciator lampcircuits, transistor 02 will be turned on. Restated, when the voltagedrop across resistor R2 decreases indicating a drop in the currentthrough an annunciator Ll lamp, transistor 01 will be turned off and thethus decreased voltage drop across resistor R6 will forward biastransistor 02. Under these conditions, with the power supply voltagepolarity being such that a positive potential appears on conductor 14,current flow through the previously described circuit including resistorR5 in the alarm panel will be shunted to neutral via transistor 02 andresistor R4. This, in turn, limits the current flowing through thesolenoid of relay RY2 causing the relay to drop out and warning buzzer42 to sound. By proper choice of the voltage rating of Zener diode 2D]and the base and collector resistors associated with the transistor 02,the current through the solenoid of relay RY2 under the shunt conditionabove described may be reduced to zero since the voltage across Zenerdiode ZDl will be less than the Zener conducting rating. In the samemanner, any open or ground condition on conductor 22 which interconnectsthe alarm and annunciator panels will also cause relay RY2 to drop outand the warning buzzer 42 to sound.

Again assuming a positive potential applied to conductor 14 from thepower source, current may flow through the alarm panel via fuse F2, thenormally closed contacts of test and reset switch S2, and through lampL2 and the Triac 44. The current may then pass, via external conductor18, from the alarm panel to the annunciator panel. In the annunciatorpanel, conductors l8 and 20 are interconnected via resistor R7 andcurrent passing through this resistor will be applied, via conductor 20,to one terminal of a first set of normally open contacts 50 of relayRY3. The line side terminal of contacts 50 of relay RY3 is connected tothe external horn circuit and the current will thus flow through theseries connected horns 30, 28 and 26 and thence through the solenoid ofrelay RY3, series connected resistor R8 and back to the neutral terminalof the power source. The voltage drop across resistor R8 provides areverse bias voltage for diode D5 which is connected between thesolenoid of relay RY3 and external conductor 22. Under any of the faultconditions previously described, or if a ground should occur in theexternal horn circuits, there will be voltage drop across resistor R8and diode D5 will conduct to shunt current normally flowing throughresistor R5 and diode D3 to ground or neutral via resistor R8. In themanner previously described, this action will also cause relay RY2 todrop out resulting in sounding of warning buzzer 42.

The above description has concentrated on the supervisory features ofthe present invention. However, the present invention also comprises analarm system; for example a fire alarm employing a plurality ofdetectors such as detectors 46 and 48. Detectors 46 and 48 may be heatdetectors, smoke detectors, manual stations, or the like. From anelectrical standpoint the detectors normally present an open circuit.However, when they are subjected to the condition to which they areresponsive, the detectors close thereby short circuiting conductors 34and 36. Thus, considering a fire alarm system, the sensing of acondition commensurate with fire by any of the external detectors willcause that detector to shunt the end of line resistor R1 thereby causingincreased current flow in the annunciator components. This increasedcurrent through the solenoid of an annunciator RYI relay will cause therelay to pick up thereby closing its contacts. In the case of relay RYl,the relay includes three pair of normally open contacts 32, 52 and 54.The closing of contacts 32 locks up the external detector circuit byestablishing a current path internally of the annunciator panel betweenconductors 34 and 36. Relay RYll thus becomes self-latching and totaldestruction of the detector which initially caused the energization ofrelay RY] will have no effect on the operation of the circuit. Theclosing of contacts 52 will place a shunt across resistor R2 causingdiode D1 to conduct and, in the manner previously described, warningbuzzer 42 in the alarm panel to sound. The shunting of the end-of-lineresistor R1 and resistor R2 by the closing of contacts 32 and 52,respectively, of relay RYl applies full line voltage to the seriesconnected solenoid of relay RY] and annunciator lamp L1 thereby causingthe annunciator lamp to light thus providing an indication of whichdetector circuit had been subjected to the unusual condition to which itis responsive. The closing of contacts 54 of relay RYl shunts resistorR7 thus causing an increase in current flow in the external horncircuit. Increased current flow in this circuit, which includes thesolenoid of relay RY3, causes this relay to pick up. The closing ofcontacts 56 of relay RY3 shunts resistor R8 whereas the closing ofcontacts 50 of relay RY3 short circuits conductors l8 and and therebycauses relay RY3 to become latched. The latching of relay RY3 by theclosing of contacts 50 results in maintaining the shunt across resistorR7 in the annunciator panel and thereby provides sufficient current tothe horn circuit to result in the sounding of horns 26 and 28 and 30.The current supplied to the horns is furnished from the Triac assembly44 and the magnitude of the current is preadjusted by means ofpotentiometer R9 which is placed in the circuit by the opening of a pairof normally closed contacts 60 of relay RY3.

Once an alarm has been sounded, means must be provided to restore normaloperating conditions. This, of course, requires the unlatching of relayRY3 and one of the annunciator panel RYl relays. This may beaccomplished by operating switch S1 on the annunciator panel tomomentarily break the circuit between the power source and the solenoidsof the RYl relays. This causes the latched relay to drop out and toaccept supervisory current upon reclosing of the normally closedcontacts of switch S1. Thereafter, reset switch S2 on the fire alarmpanel may be depressed momentarily disrupting current to the solenoid ofrelay RY3 thereby causing this relay to drop out thereby returning itscontacts to normal, the relay solenoid accepting normal supervisorycurrent upon reclosure of switch S2. Thus, it may be seen that an alarmcondition will be maintained even if the alarm initiating device andannunciator control panels were damaged by spreading fire prior toresponse to the alarm.

Even though sufficient current will not normally flow through thefilaments of the annunciator panel Ll lamps the filaments in these lampswill ultimately burn out or break. This, of course, will result in theforward biasing of the associated D1 diode and the sounding of thewarning buzzer 42 in the manner above-described. When this happens,visual observation of the annunciator panel will not, of course, providean indication as to the circuit in which the trouble is occurring.However, the particular lamp which is opened may be isolated immediatelyby momentarily operating switch S1 to complete a circuit which willenergize all of the annunciator panel lamps. Assuming that the sourcepolarity is such that a negative potential is applied to conductor 14,with the normally open contacts of switch S1 closed a current path isprovided from the neutral or ground conductor 16 to all of the D1 diodesvia diode D8 and conductor 38. Each of the annunciator circuit D1 diodeswill thus provide current to the lamp associated with its circuit,current being provided via fuse F3 and the D6 diodes which are connectedbetween the annunciator L1 lamps and fuse F3. Thus, all good lamps willlight at half brilliance, current being blocked by the D6 diodes duringpositive half cycles of the supply voltage, and the open lamp may beisolated immediately. Upon replacement of the fault lamp, the warningbuzzer 42 will cease operating indicating restoration of normalconditions on all circuits.

A D7 diode is provided in each of the annunciator circuits to prevent analarm condition if external conductor 36 of the detector circuits shouldinadvertently become grounded. Normally, such a ground condition wouldcause a trouble signal and the normal response of a technician would beto operate switch S1 momentarily to check the annunciator lamps.However, with conductor 36 grounded, the closing of switch S1 to itslower (normally open) contact will provide a path from ground to thesource via the solenoid of an RYl relay, a D6 diode. and fuse F3.Current flowing through such a circuit could cause an annunciator relayto pick up and lock up the fire alarm panel in an identical manner aspreviously described in the case of an actual alarm. To prevent thisoccurring, diodes D7 are provided in the circuit to establish a currentpath from ground to source which bypasses the solenoid of the RYllrelay, the current passed by the D7 diodes generally being sufficient toblow the F3 fuse which protects the diodes. lt should also be noted thata Zener diode ZD2 is provided to protect transistors Q11 and Q2 fromtransients or overvoltage conditions on the alternating current supplyline.

Returning again to a consideration of the alarm panel 10, a particularlyunique feature of this circuit is the provision of lamp L2 in serieswith the Triac 44 to compensate the Triac phase shift gating network forline voltage variations. It has been discovered that the temperaturecoefficient characteristic of the tungsten filament in lamp L2 providesan additional voltage drop between the phase shift network and the Triacemitter to thereby stabilize Triac signal current under varyingconditions of supply line voltage.

From the foregoing description, it will be apparent to those skilled inthe art that the supervised annunciator alarm system of the presentinvention can be expanded and integrated wit other common alarm featuressuch as external trouble signals, for which a terminal 62 is provided,trouble re-ring circuits, auxiliary relays for city tie, zone codingtransmitters which may be tripped by annunciator relay contacts,additional horn circuits, presignal circuits and other concepts whichare old in the art.

It is to be noted that the circuitry discussed above has beenspecifically described for alternating current supply applications.However, the system of monitoring or supervising and controllingmultiple circuits of the present invention is also applicable to directcurrent applications as well. In the case of direct current supply, theTriac alternating current control would be replaced by a transistor,variable resistor, or other ballast means.

To summarize the operation and advantages of the present invention, inthe supervisory circuits the neutral terminal 16 will be at groundpotential and any ground or open in the annunciator or alarm panelcircuitry will cause relay RY2 to drop out and energize warning buzzer42. In addition, an open in the conductor 16 between the annunciator andalarm panels will cause relay RY2 to chatter thereby also providing anaudible warning. Thus, all lamps, fuses, external wiring and interwiringbetween the panels are supervised for functional capability. Thissupervision for opens and grounds of multiple circuits is accomplishedwith the single RY2. Also, the supervision of the remote annunciatorpanel 12 is accomplished with a minimum of interconnecting conductorsbetween the annunciator panel and the main fire alarm panel 110.

An additional advantage of the present invention, as previously noted,is the use of a solid state Triac ballast for the external horn circuitsthereby achieving a brightening of the tone of the horns due to the highharmonic content of the output wave form of the Triac.

A particularly advantageous feature of the present invention is thatadditional detector circuits may be added later without providing foradditional interwiring between the main fire alarm panel and theannunciator panel and such detector circuits may be added withoutdisturbing existing supervisory wiring within the annunciator. Forexample, an additional D1 diode is all that is required to supervise anadditional circuit and such a diode may be added without disrupting orbreaking the lines of any previously existing circuits.

While a preferred embodiment has been described, it is to be noted thatvarious modifications and substitutions may be made thereto withoutdeparting from the spirit and scope of the present invention.Accordingly, it is to be understood that the present invention has beendescribed by way of illustration and not limitation.

What I claim is:

1. An annunciated alarm system comprising:

condition responsive means;

normally inoperative annunciator means connected in a series with saidcondition responsive means;

means for supplying supervisory current to said annunciator means;

first switch means electrically connected to said annunciator means andresponsive to a failure of the supervisory current'flow, said switchmeans normally presenting an open circuit to current flow;

malfunction warning means; and

means electrically connected to said switch means and to said warningmeans for energizing said warning means upon operation of said switchmeans in response to a failure of supervisory current flow.

2. The apparatus of claim I wherein said warning means is located on analarm panel and said annunciator means comprises a remotely locatedannunciator panel, said panels being interconnected by a plurality ofconductors, and wherein said energizing means comprises:

normally open second switch means connected in series with said warningmeans, said second switch means being in a normally energized statewhereby operation of said first switch means or a malfunction in thewiring interconnecting the panels will cause deenergization of saidsecond switch means and coincident closing thereof to complete a circuitto said warning means.

3. The apparatus of claim 2 further comprising:

alarm means;

means for supplying current to said alarm means; and

means connecting said current supply means to said alarm means, saidconnecting means including first current limiting means connected inseries with said alarm means.

4. The apparatus of claim I wherein said means for supplying supervisorycurrent to said annunciator means comprises:

second current limiting means connected in parallel with said conditionresponsive means.

5. The apparatus of claim 4 wherein said condition responsive meansnormally presents an open circuit and wherein said annunciator meanscomprises:

self-latching relay means, a first set of normally open contacts of saidrelay means establishing a short of circuit across said conditionresponsive means and said second current responsive means uponenergization of said relay means in response to operation of saidcondition responsive means to create a temporary shunt across saidsecond current limiting means.

6. The apparatus of claim 3 wherein said means for supplying supervisorycurrent to said annunciator means comprises:

second current limiting means connected in parallel with said conditionresponsive means.

7. The apparatus of claim 6 wherein said condition responsive meansnormally presents an open circuit and wherein said annunciator meanscomprises:

self-latching relay means, a first set of normally open contacts of saidrelay means establishing a short circuit across said conditionresponsive means and said second current responsive means uponenergization of said relay means in response to operation of saidcondition responsive means to create a temporary shunt across saidsecond current limiting means.

8. The apparatus of claim 7 wherein said annunciator means furthercomprises:

a second set of normally open contacts, said second set of contactsbeing connected in parallel with said first current limiting meanswhereby energization of said relay means short circuits said firstcurrent limiting means and said alarm means are energized by theincreased current. 9. The apparatus of claim I wherein said first switchmeans comprises:

a first normally conducting transistor, normally reverse biased diodemeans connected between said annunciator and the base of said firsttransistor, a decrease in supervisory current causing said diode toconduct, conduction of said diode causing a decrease in the forward biasvoltage on said first transistor whereby said first transistor isswitched to a nonconductive state; and means connected to saidenergizing means and responsive to the switching of said firsttransistor for deenergizing said energizing means. 10. The apparatus ofclaim 8 wherein said first switch means comprises: 1

a first normally conducting transistor, normally reverse biased diodemeans connected between said annunciator and the base of said firsttransistor, a decrease in supervisory current causing said diode toconduct, conduction of said diode causing a decrease in the forward biasvoltage on said first transistor whereby said first transistor isswitched to a nonconductive state; and means connected to saidenergizing means and responsive to the switching of said firsttransistor for deenergizing said energizing means. 11. The apparatus ofclaim 10 wherein said means for supplying current to said alarm meansincludes: a bidirectional silicon controlled rectifier.

Patent No.

Inventor(s) (SEAL Attes EDWAR Filing Date:

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Leonard E. EarlingIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

2, line 64: Change 4, line 51: Change 5, line 71: Change 6, line 30:Change 7, line 49: Change --a short circuit--.

Signed and sealed this 16th day of November 1971 D M.FLETCHER,JR.

Attesting Officer Change "June 7, 1968" to --May 7, 1968--.

ROBERT GO'ITSCHALK Acting Commissioner of Patents Dated June 22 1971"components" to --components,--.

"be voltage" to --be no voltage-1.

"fault" to -faulty-.

"wit to --with-.

"a short of circuit" to F ORM PO-105O 110-69!

1. An annunciated alarm system comprising: condition responsive means;normally inoperative annunciator means connected in a series with saidcondition responsive means; means for supplying supervisory current tosaid annunciator means; first switch means electrically connected tosaid annunciator means and responsive to a failure of the supervisorycurrent flow, said switch means normally presenting an open circuit tocurrent flow; malfunction warning means; and means electricallyconnected to said switch means and to said warning means for energizingsaid warning means upon operation of said switch means in response to afailure of supervisory current flow.
 2. The apparatus of claim 1 whereinsaid warning means is located on an alarm panel and said annunciatormeans comprises a remotely located annunciator panel, said panels beinginterconnected by a plurality of conductorS, and wherein said energizingmeans comprises: normally open second switch means connected in serieswith said warning means, said second switch means being in a normallyenergized state whereby operation of said first switch means or amalfunction in the wiring interconnecting the panels will causedeenergization of said second switch means and coincident closingthereof to complete a circuit to said warning means.
 3. The apparatus ofclaim 2 further comprising: alarm means; means for supplying current tosaid alarm means; and means connecting said current supply means to saidalarm means, said connecting means including first current limitingmeans connected in series with said alarm means.
 4. The apparatus ofclaim 1 wherein said means for supplying supervisory current to saidannunciator means comprises: second current limiting means connected inparallel with said condition responsive means.
 5. The apparatus of claim4 wherein said condition responsive means normally presents an opencircuit and wherein said annunciator means comprises: self-latchingrelay means, a first set of normally open contacts of said relay meansestablishing a short of circuit across said condition responsive meansand said second current responsive means upon energization of said relaymeans in response to operation of said condition responsive means tocreate a temporary shunt across said second current limiting means. 6.The apparatus of claim 3 wherein said means for supplying supervisorycurrent to said annunciator means comprises: second current limitingmeans connected in parallel with said condition responsive means.
 7. Theapparatus of claim 6 wherein said condition responsive means normallypresents an open circuit and wherein said annunciator means comprises:self-latching relay means, a first set of normally open contacts of saidrelay means establishing a short circuit across said conditionresponsive means and said second current responsive means uponenergization of said relay means in response to operation of saidcondition responsive means to create a temporary shunt across saidsecond current limiting means.
 8. The apparatus of claim 7 wherein saidannunciator means further comprises: a second set of normally opencontacts, said second set of contacts being connected in parallel withsaid first current limiting means whereby energization of said relaymeans short circuits said first current limiting means and said alarmmeans are energized by the increased current.
 9. The apparatus of claim1 wherein said first switch means comprises: a first normally conductingtransistor, normally reverse biased diode means connected between saidannunciator and the base of said first transistor, a decrease insupervisory current causing said diode to conduct, conduction of saiddiode causing a decrease in the forward bias voltage on said firsttransistor whereby said first transistor is switched to a nonconductivestate; and means connected to said energizing means and responsive tothe switching of said first transistor for deenergizing said energizingmeans.
 10. The apparatus of claim 8 wherein said first switch meanscomprises: a first normally conducting transistor, normally reversebiased diode means connected between said annunciator and the base ofsaid first transistor, a decrease in supervisory current causing saiddiode to conduct, conduction of said diode causing a decrease in theforward bias voltage on said first transistor whereby said firsttransistor is switched to a nonconductive state; and means connected tosaid energizing means and responsive to the switching of said firsttransistor for deenergizing said energizing means.
 11. The apparatus ofclaim 10 wherein said means for supplying current to said alarm meansincludes: a bidirectional silicon controlled rectifier.